A refrigeration cycle apparatus includes, for example, a compressor that compresses and discharges refrigerant, a heat exchanger serving as a radiator (a condenser) that transfers heat from the refrigerant, and a heat exchanger serving as an expansion device that reduces the pressure of the refrigerant and an evaporator that causes the refrigerant to evaporate.
The compressor includes, for example, a sealed container defining the exterior, a motor mechanism including a stator fixed in the sealed container and a rotor, and a compression mechanism that is driven by the motor mechanism and compresses the refrigerant.
If the compressor is of the rotary type, a piston slides on a cylinder of the compression mechanism of the compressor when compressing the refrigerant. The sliding of the cylinder and the piston causes wear of the both parts, leading to a reduction in reliability of the compressor. That is, since the compressor includes various sliding parts, the sliding parts are worn, leading to a reduction in reliability. To avoid this, refrigerating machine oil serving as a lubricant is sealed in the sealed container of the compressor. The refrigerating machine oil flows between the cylinder and the piston, together with the refrigerant, and lubricates the cylinder and the piston.
In the sealed container, the refrigerating machine oil is mixed in the refrigerant. Therefore, when the amount of liquid refrigerant in the sealed container increases (the liquid back amount increases), the concentration of the refrigerating machine oil in the sealed container decreases, which may result in poor lubrication. In view of the above, there has been proposed a refrigeration cycle apparatus (a refrigerating machine) that temporarily stops the compressor when the liquid back amount increases (see, for example, Patent Literature 1).